The present project is a continuation of our ongoing research on homolytic aromatic hydroxylation via OH radicals and via radical cation. Most chemicals are not mutagenic or carcinogenic per se but have to be transformed metabolically to the ultimate carcinogenic form. Some of these processes involve dihydrodiol, epoxide and dialdehyde formation. We are continuing our studies on the detailed chemical mechanisms which can accomplish these transformations. These reactions involve metal ion - H2O2, metal ion - O2, metal ion - ascorbic acid - O2 systems with aromatics and olefins. Some of these systems have been recently reviewed by us (manuscript II, appendix). We plan to continue our studies on radiation induced formation of radical cations, OH and O2- radicals in absence of metal ions in order to assess the role of metal ions in the above mentioned processes. These purely chemical transformations most likely play an important role in the activation of precarcinogens via failed phagocytosis. One such example is the activation of B(a)P by asbestos stimulated macrophages. Oxygen radicals are increasingly recognized as the cause of many disease processes, including cancer, heart disease, stroke and emphysema. The study of these reactive radicals with organic molecules is therefore important for the better understanding of many disease processes.